It will work depending on template region and primer sequence. You might need betaine for tricky targets..!!

Heparin will interfere with the PCR (will bind Mg++) , otherwise you can do PCR directly from blood or dried blood spots on paper (Gutrie cards), you should only use small amount blood and lots of BSA 

Peter is right, heparin is a chelator.  However, if there are no other samples available, one can add  excess Mg++ to overcome the inhibition.  Be careful not to add too much of Mg either.

In late 80's I worked on the effect of anticoagulants on PCR.  I Since most of the anticoagulants are metal chelators, I believe one has to neutralize the chelator one way or other. 

Thank you for your valuable answers to every one